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lieven lebruyn
Works at University of Antwerp
Attended Universiteit Antwerpen
Lives in Antwerp,Belgium
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lieven lebruyn

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Proud to be working at a well-known university
First time I'm mentioned in "Nature", they issue this correction:
Corrected: An earlier version of this story incorrectly located the University of Antwerp in the Netherlands. It is in Belgium. The text has been updated.

Not particularly proud of the quote they took from my blog though:

“Is it just me, or is Mochizuki really sticking up his middle finger to the mathematical community”.

In celebration, i've put that 'lost' post back online (for now):
A Japanese mathematician claims to have solved one of the most important problems in his field.
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Grothendieck's later writings   #Grothendieck

Next week there's a Grothendieck conference at Montpellier George Maltsiniotis will give a talk thursday afternoon with the  exciting title "Grothendieck's manuscripts in Lasserre" (hat tip +Pieter Belmans ).

You may recall that G's last hideout was in the Pyrenean village of Lasserre

After a bit of sleuthing around I've heard some great news.

Grothendieck's family have donated all of his later writings (apart from his correspondences and other family-related stuff) to the Bibliotheque Nationale. The BNF have expressed their intention of scanning all this material (thousands of pages it seems) and making them (eventually) available online!

Rumour has it that the donation consists of 41 large folders containing G's reflections, kept in the form of a diary (a bit like 'Clef des Songes', on G's usual suspects (evil, Satan, the cosmos), but 2 or 3 of these folders contain mathematics (of sorts).

Probably, Maltsiniotis will give a preview on this material. To anyone lucky enough to be able to go down south next week and to attend his talk, please keep me in the loop...
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+David Roberts i guess this concerns
the BNF-catalogue mentions a printed text and the later writings are mostly handwritten. 
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Mochizuki in denial

From M's 2014 IUTeich-Progress-Report (17 pages, the 2013-edition was only 7 pages long):

"Activities surrounding IUTeich appears to be in a stage of transition from a focus on verification to a focus on dissemination."

If only... 

He further lists hypotheses as to why nobody (apart from his 3 disciples Yamashita,Saidi and Hoshi) makes a serious effort to  "study the theory carefully and systematically from the beginning":

1. it is too long (1500-2500 pages)
2. there's lack of textbooks on anabelian geometry
3. we are obsessed with the Langlands program
4. there's little room for generalisations
5. it may not be directly useful for our own research

But then, why should anyone make such an effort, as:

"With the exception of the handful of researchers already involved in the verification activities concerning IUTeich, every researcher in arithmetic geometry throughout the world is a complete novice with respect to the mathematics surrounding IUTeich, and hence, in particular, is simply not qualified to issue a definite judgment concerning the validity of IUTeich on the basis of a 'deep understanding' arising from his/her previous research achievements."

No Mochizuki, the next phase will not be dissemination, it will be denial.

Other remarkable sentences are:

"IUTeich is 'the correct theory' in the sense that it leads one to doubt the existence of any sort of 'alternative proof', i.e. via essentially different techniques, of the ABC Conjecture."


"the status of IUTeich in the field of arithmetic geometry constitutes a sort of faithful miniature model of the status of pure mathematics in human society."

Already looking forward to the 2015 'progress' report...


#Mochizuki, #IUTeich  
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+john iskra​ I would say that Lieven did some work to illuminate the concept of Frobenioid, with the view to IUTT, rather that the IUTT itself (and by his own admission, if I recall correctly). Minyong's MO postings are the only 'independent' exposition of the ideas M uses that I know of.
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#Grothendieck   #Bourbaki  
Nicolas Bourbaki is temporarily resurrected to announce the death of Grothendieck in the French newspaper Le Monde.
You may recall that Bourbaki passed away on november 11th 1968, see +Peter Luschny's post on his death announcement here :
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Mormoiron and Lasserre acknowledge Grothendieck

In the series of post on Grothendieck-places I wrote a year ago (see and links at the end) I tried to convince these French villages to update their Wikipedia page to acknowledge the existence of Grothendieck under the heading 'Personnalités liées à la commune', without much success.

Today it is nice to see that Lasserre added Grothendieck to their page ( :
"Alexandre Grothendieck (1928-2014), considéré comme un des plus grands mathématiciens du xxe siècle, y a vécu en quasi-ermite de 1990 à sa mort."

Also Mormoiron, where Grothendieck lived in the 80ties (see picture below) has updated its page (
"Alexandre Grothendieck a habité temporairement à Mormoiron ("Les Aumettes")"

French villages who still have to follow suit:
- Vendargues :
- Massy :
- Olmet-et-Villecun :

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+guy yak I would understand this from Lasserre's POV as he lived there until his death last thursday, but what about the other villages where he has lived for years in a far and distant past? 
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Fresh(wo)men's course on Foundations

In two months I’ll be teaching ‘Logic and Set Theory’ for the first time, a first year, first semester course on Foundations. And no (though I considered it for a nanosecond) I will not trow HoTT at them…

There are few thing I like more than composing a new course. In the Belgian (university) system, a teacher is completely free to decide the content of his/her course. Clearly, there are the expectations of colleagues on what the course should (minimally) contain.

For this first semester, first year course I know I have to tell them about sets, maps, relations, truth tables, quantifiers, real numbers, and, perhaps, something about the axiom of choice and Zorn’s lemma. Btw.the guy in the picture  is Anders Zorn.

Earlier this week I began LaTeXing the notes, starting with the naive view on sets and their operations (intersection, union, subsets, power sets, products,…) and maps (images, inverse images, injective, surjective, bijective,…) but got quickly bored, as would be the students I guess.

The plan now will be to end this first 2 hour block with something a bit more fun: the notion of cardinality, proving that Q can be enumerated, Cantor’s diagonal argument that R cannot and, as a possible application of power sets, that here will always be a still higher cardinality.

I chuckled while typing the final line of that first session: “Nobody knows whether c=aleph1, that’s called the continuum hypothesis”… Hope this will blow their minds out, the first week of math-school.

The present plan of the other lessons can found on my new blog

All suggestions are welcome!

(Added august 3): Oops added a photograph of the wrong Zorn, Anders the artist, not Max the mathematician....
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+Toby Bartels "and furthermore we can PROVE that nobody knows! " : nice suggestion!
Anyway, im now TeXing completeness and compactness of propositional calculus, perhaps someone should clarify/clean up the mess Wikipidia makes of this.
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Maltsiniotis' talk on Grothendieck's Lasserre-gribouillis   #Grothendieck

Yesterday, George Maltsiniotis gave a talk at the Gothendieck conference in Montpellier with title "Grothendieck's manuscripts in Lasserre" [1].

This morning, +David Roberts  asked for more information on its content, and earlier i gave a short reply on what i learned [2], but perhaps this matter deserves a more careful write-up.

+Damien Calaque  attended George's talk and all info below is based on his recollections. Damien stresses that he didn't take notes so there might be minor errors in the titles and order of the parts mentioned below.

EDIT: based on info i got from +Pieter Belmans  in the comments below (followed up by the picture he got via +Adeel Khan  taken by Edouard Balzin) i've corrected the order and added additional info.

 The talk was videotaped and should become public soon.

As i mentioned last week [3] Grothendieck's family has handed over all non-family related material to the Bibliotheque Nationale. Two days ago, Le Monde wrote [4] that the legacy consists of some 50.000 pages.

Maltsiniotis insisted that the BNF wants to make these notes available to the academic community, after they made an inventory (which may take some time).

I guess from the blackboard-picture i got from Pieter, the person responsible at the BNF is Isabelle le Masme de Chermont [7].

The Lasserre-griboillis themselves consists of 5 parts:

1. Géométrie élémentaire schématique. (August 1992)
This is about quadratic forms and seems to be really elementary.

2. Structure de la psyché. (12/10/1992-28/09/1993) 3600 pages
This one is about some combinatorics of oriented graphs with extra-structure (part of the structure are successor and predecessor operators on the set of arrows).

3. Psyché et structures (26/03/93-20/06/93) 700 pages
This one is non-mathematical.

4. Maxwell equations.
Maltsiniotis mentioned that he was surprised to see that there was at best one mathematics book in G's home, but plenty of physics books.

5. Le problème du mal. (1993-1998) 
This one is huge (30.000 pages) and is non-mathematical.

Note that also the Mormoiron-gribouillis will be made public by the University of Montpellier, [5] or if you prefer video [6].

Finally, is the photo below what you think it is? Yep!

[1] :
[2] :
[3] :
[4] :
[5] :
[6] :
[7] :
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Do you know where one finds the videos?
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wOZ declares 2015 mathematically sound!

“2015 is mathematically sound.
20 is 4*5 and 15 is 3*5. 2015 is 5*13*31. 13 and 31 are reversed digit prime numbers.
In binary 2015 is 11111011111, a palindrome.
2015 is also 3737 in base 8 (octal) and 37 is the most special number of all in my opinion. For one thing, it’s the best age. For another, it’s the first irregular prime number!"

a math-happy 2015 :: lieven.
Woz wishes us all a 'mathematically sound' New Year
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The 'avis de décès' released by Grothendieck's family and friends, published in the local French newspaper 'La Depeche', on saturday november 15th.

It announces Grothendieck's cremation, on november 17th at 11.30h in the village of Pamiers, bordering the 'Camp du Vernet', where Grothendieck's father Sasha was imprisoned, before being deported to Auschwitz and murdered by the Nazis in 1942. 
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Please keep an eye on the GrothendieckCircle for updates

+Leila Schneps invested a lot of time over the years setting up the Grothendieck Circle website

Some material had to be removed a few years ago as per Groth's request.

I'm sure many of you will be as thrilled as I was to get this message from Leila:

"I have already started modifying the Grothendieck circle website and it will of course eventually return completely.  Plus many things will be added, as we will now have access to Grothendieck's correspondence and many other papers."

Leila already began to update the site, for example there's this new page on Groth's life in Lasserre:

I understand Leila is traveling to Lasserre tomorrow, presumably for Grothendieck's funeral. Hopefully she will eventually post something about it on the GrothendieckCircle (or, why not here on G+).

The village of Lasserre - 200 residents - where Grothendieck lived as a recluse for over 23 years. The house where he lived. He took loving care of the plants and flowers, bringing shoots indoors to nourish them in individual pots. He made soup from his dandelions and once, long ago, ...
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+Felipe Voloch : settled now. perhaps they took the site offline over the weekend to update some pages. The Lasserre-page sure has been updated.
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Grothendieck's last hideout

The past ten days I've been up in the French mountains (without internet access), not that far from the Ariege, so I'm just now catching up with all (blog)posts related to Grothendieck's death.
At our place, the morning of thursday november 13th was glorious!
Even though FranceInter kept telling horror stories about flooding in more southern departements, I can only hope that Grothendieck passed away in that morning sun.
About a year ago, on the occasion of Groth's 85th birthday, I ran a series of posts on places where he used to live, ending with his last known hideout:
At the time I didn't include the precise location of his house, but now that pictures of it are in the French press I feel free to suggest (if you are interested to know where Grothendieck spend his later years) to point your Google-earth or Google-maps (in streetview!) to:
lat 43.068254  lon 1.169080
Certains le considèrent comme «le plus grand mathématicien du XXe siècle». Alexandre Grothendieck est décédé jeudi. Il s'était installé à Lasserre pour s'isoler. Les habitants connaissaient l'existence de cet homme discret, sans le fréquenter. ...
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For the few persisting  #Mochizuki  watchers: there's some activity at the twitter feed
Chung Pang Mok is touring Universities with an "introductory" talk to IUTeich. he's scheduled at University of British Columbia, Duke, UCSC, MSRI, possibly others.
If someone attended and saw a glimpse of light towards the end of the tunnel, please share!
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Mathematician at UA
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mathematician by day, blogger by night
early adopter of noncommutative geometry, sceptic evangelist of the 'field with one element', passionate about a 400 year old chestnut farm somewhere in the Cevennes.
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